The present invention addresses the sector of packaging groups of products by wrapping them in tubular film lengths.
This invention relates in particular to the sector of packaging with stretch film, where the film is not heated but applied cold, stretched over the groups of products to be wrapped and left to return to its original size, thanks to its elastic properties, to form individual packs in which the products are held together tightly.
At present, machines for stretch wrapping groups of products are well known. These machines typically comprise several operating stations designed to receive groups of products and to wrap each group with a length of stretch film.
In particular, patent IT1285827 to the same Applicant as the present discloses a machine and a method for wrapping groups of products in tubular stretch film lengths.
The machine described in that patent comprises a station for feeding tubular film lengths to a stretching device where a set of reciprocally mobile parallel rods engage the tube of film lengthwise.
After receiving the film, the stretching device moves towards a placing station and, while doing so, stretches the tube of film to the size and shape matching that of the group of products waiting to be wrapped at the placing and unloading station.
At this station, the group of products is inserted into the tube which, on being released by the bars, tends to return to its original size over the group of products in such a way as to form a pack which is then unloaded.
More particularly, this type of machine has a revolver-like structure comprising a plurality of stretching devices arranged in a circle and made to move one after the other first through the feed station and then through the placing and unloading station.
A machine designed in this way has the advantage of offering high productivity in a limited space and making a continuous flow of packages whose formation is synchronized with the feeding of the film tubes to the placing station and hence with the speed of carousel rotation.
The disadvantage of the solution described above, however, is that the carousel has to bear the full weight of the actuators necessary for fully stretching the film, which considerably complicates and encumbers the machine structure, especially if the machine has two or more stretching units.
A first aim of the present invention is to overcome the above mentioned disadvantage by providing a high productivity machine with a relatively simple structure.